Realization of a compact cross-grating spectrometer and validating experimental tests.

Echelle inspired cross-grating spectrometers offer the potential to bridge the gap between classical high-end echelle spectrometers and curved-grating single-element instruments. In particular, the cross-grating approach offers the possibility to simultaneously achieve a high spectral resolution and a wide accessible spectral range in compact dimensions and without moving parts. We report on the complete realization and implementation details of an all-reflective cross-grating spectrometer based on a modified Czerny-Turner configuration including a folded beam path and a toric-convex mirror for aberration compensation. The applicability of the cross-grating spectrometer is demonstrated by test measurements including the recording of the spectra of different plant leaves. For the cross-grating spectrometer, with an accessible wavelength range between 330 and 1100 nm, a spectral resolution of 0.6 nm at 589 nm was achieved.

Concept and optical design of a compact cross-grating spectrometer.

The concept of a new compact echelle-inspired cross-grating spectrometer is introduced, and a specific optical design is presented. The new concept aims to achieve simultaneously a high spectral resolution, a wide accessible spectral range, and compact dimensions. The essential system novelty concerns the combination of different aspects: the implementation of a crossed grating comprising both the main dispersion and order separation, a folded reflective beam path, which enables a reduction of the system volume, and the introduction of a form-adjustable mirror for aberration compensation. The exemplary optical design offers a spectral bandwidth ranging from 330-1100 nm with spectral resolution better than 1.4 nm in the fourth and 0.4 nm in the 11th order. The optical setup covers a volume of 110 mm×110 mm×30 mm.

Compact echelle spectrometer employing a cross-grating.

The concept and the implementation of a compact and simplified echelle spectrometer are presented, and the working principle is demonstrated by first experimental measurements. The crucial element of the setup is a cross-grating, combining an echelle grating utilizing several higher diffraction orders (5th up to 11th) and a superposed perpendicular-oriented cross-dispersing grating. Two alternative manufacturing approaches for the cross-grating are presented and discussed. The first approach combines Talbot lithography for the deep echelle grating and interference lithography for the cross-dispersing structure. As a second approach, direct laser-beam writing was applied. The compact echelle spectrometer covers a spectral range from 380 to 700 nm and offers a spectral resolution of ∼2 nm.